1. Field of the Invention
This invention relates to refrigeration and more particularly to a system in which the advantages of a gas-liquid intercooler are provided with the ability to maintain the desired pressure for insuring adequate flow to the evaporators and in which a high level of safety protection to the compressor is provided.
2. Description of the Prior Art
A compound pressurized recirculation refrigeration system having a shell type vessel providing a combination flash liquid cooler and first stage gas cooler is disclosed in Ross U.S. Pat. No. 3,919,859. However, in such system no subcooling of the liquid for delivery purposes is provided. Thus, in this patent the liquid supplied to the evaporator is at the saturation temperature and therefore a further pressure drop in the line to the evaporator will result in the production of undesired flash gas at the control of the evaporator. Further, the liquid being delivered to the evaporator through line 15 is at an intermediate pressure in the compound system and thus there would not be a pressure difference on the liquid adequate for delivery thereof to high stage evaporators.
Garland U.S. Pat. No. 3,797,265 discloses a single stage system providing a pressurized refrigerant feed with recirculation.
The use of gas-liquid intercoolers has been known as, for example, disclosed in Zumbro U.S. Pat. No. 2,553,623.
Ross U.S. Pat. No. 2,966,043 discloses the flowing of liquid refrigerant directly into a suction line accumulator tank 24 which is in heat exchange relationship with a coil carrying liquid to high temperature evaporators. Liquid from the high temperature accumulator passes into a coil in heat exchange relationship in a low temperature accumulator 36. In Ross, both the high and low temperature accumulators maintain a liquid level in order to function as heat exchangers. Thus, each of the accumulators in Ross also function as the return liquid separator from its respective evaporator. In Ross the liquid feed to the low temperature evaporators is at an intermediate pressure instead of at a higher pressure. Furthermore, the liquid level in the high temperature accumulator 24 of Ross is fixed only when the tank 41 is not transferring. During such transfer, liquid level in the accumulator 24 increases.
In Ross U.S. Pat. No. 2,966,043 the liquid used for the purpose of cooling in accumulator 24, FIG. 1, is obtained from the second or low pressure receiver 30; in FIG. 2 from the receiver 68; in FIG. 3 from the receiver 115. FIG. 4 of Ross U.S. Pat. No. 2,966,043 discloses a single stage operation which uses a pilot receiver and a coil for liquid cooling in the return separator.
Other U.S. Pat. Nos. illustrating the prior art include Richard 2,841,962; Blake 3,150,498; and Blake 3,184,926.